The invention relates to a gas valve unit for adjusting gas volume flows to a dual circuit gas burner of a gas appliance, in particular gas cooking appliance, wherein the gas valve unit comprises a gas inlet and two gas outlets.
Gas burners having two concentrically-disposed rings with a gas outlet openings are frequently used in gas cooking appliances. During the operation of the gas hob, a flame ring can burn at each of the rings with gas outlet openings. When the gas volume flows to the two rings with gas outlet openings are able to be adjusted separately, these gas burners are referred to as dual circuit gas burners. By comparison with conventional gas burners with only one flame ring, dual circuit gas burners generally possess a greater maximum burner power. In addition dual circuit gas burners possess an especially large spread between minimum burner power and maximum burner power. At maximum burner power both flame rings burn with the largest possible flames. At minimum burner power only the smaller flame ring burns with the smallest possible flames, while no gas flows out of the larger ring with flame outlet openings.
Gas valves for supply of dual circuit gas valves possess a gas input with which the gas valve is connected to a main gas line of the gas cooking appliance. A first gas output of the gas valve opens out into a first part gas line leading to the smaller ring with gas outlet openings. A second gas outlet is connected to a second part gas line leading to the larger ring with gas outlet openings.
Dual circuit gas valves possess a single actuation element with which both the gas flow for supplying the first flame ring and also the gas flow for supplying the second flame ring can be adjusted. In accordance with a first possible design of the dual circuit gas valve, starting from a completely closed dual circuit gas valve, on actuation of the actuation element the gas flow is first opened to the smaller ring with gas outlet openings. Subsequently when the smaller flame ring has reached its maximum power, the gas flow to the larger ring with gas outlet openings is also opened, until the larger flame ring has also reached its maximum power. In accordance with a second possible design the completely closed position of the dual circuit gas valve is directly followed by the switch position for maximum power of both flame rings. A further actuation of the control element initially reduces the power of the larger flame ring, until this is extinguished completely. Subsequently the power of the smaller flame ring is reduced until this has reached its minimum power. In both the embodiments, depending on the position of the actuation element, either the dual circuit gas valve is completely closed or exclusively the gas flow to the smaller ring with gas outlet openings is opened or the gas flow to both rings with gas outlet openings is opened. On the other hand there is no provision for closing the gas flow to the smaller ring with gas outlet openings while the gas flow to the larger ring with gas outlet openings is opened.
Known gas valve units for dual circuit gas burners are generally designed as plug valves, in which a valve plug is rotated into a valve housing by means of the actuation element. With these known valves the exact setting of a desired burner power as well as the reproducibility of such a setting proves difficult.